Paper waste constitutes 31% of all residential and commercial waste by weight and well over half by volume in the United States. Office waste paper from laser printers, photocopiers and facsimile machines comprise a significant portion of the total amount of waste paper in the U.S.
Printing on paper is accomplished by using two types of inks, namely, impact and non-impact. Impact inks are those produced by, for example, letter press and lithography techniques. Non-impact inks or "laser" inks are those produced, for example, in laser printing, photocopying and in facsimile machines. With impact printing the ink does not fuse into the paper and is, therefore, easy to remove from the paper. Papers printed on with impact methods have been successfully deinked for years. However, non-impact ink, i.e. toner, is difficult to remove because the ink particles fuse into the paper and to one another.
Presently, paper printed on with non-impact ink is recycled in large quantities in paper mill environments. Typically, that paper in large quantities is submitted to a chemical tank to soften the toner and the paper is then repulped to remove the toner. This process is expensive and does not produce high quality recycled paper. Moreover, there is a significant cost to individuals who recycle for hauling the paper to the remote recycling locations.
Small scale, individual recycling units which remove toner and are capable of recycling paper printed on with non-impact inks have been developed. One such device disclosed in U.S. Pat. No. 5,463,447 to Kurotori et al., removes toner from sheets of paper which was printed thereon by a photocopier. However, that device requires that the developer used in the photocopier be improved such that the adhering force of the toner is weak enough to allow the toner to be subsequently removed from the paper on which a toner image is formed. Thus, the device of that patent does not properly deink paper unless it was first printed on with a toner having a sufficiently weak adhering force.
Another device disclosed in U.S. Pat. No. 5,353,108 to Tsukamoto is used for cleaning printed paper, however, the paper to be cleaned must be erasable paper comprised of a substrate and a releasing layer. The paper is fed between an adhesion roller and a platen. There is a heat soluble resin in molten state on the surface of the adhesion roller and heat applied to the heat soluble resin by means of a heat source causes heat-soluble ink on the erasable paper to be enveloped therein and peeled from the surface of the paper.
These devices have very limited applications and may not be used generally with any piece of paper containing non-impact ink. That is, they are only useful with certain types of used paper, e.g. erasable, or with used paper that contains a specific toner with weak adhering forces.
Therefore, there is a need for a method and apparatus which is capable of deinking paper containing non-impact ink regardless of the type of paper or toner used in the printing process and one that will accomplish these objectives inexpensively and locally on a relatively small scale.